In a groundbreaking discovery that reshapes our understanding of squamate evolution, an international team of paleontologists has unveiled a remarkably well-preserved fossil species from the Jurassic period that exhibits an extraordinary blend of anatomical features reminiscent of both snakes and lizards. The specimen, named Breugnathair elgolensis, meaning “false snake of Elgol,” was unearthed in Scotland’s Isle of Skye and represents one of the oldest largely complete lizard fossils ever found, offering new insights into the elusive origins of snakes and their evolutionary relatives.
Breugnathair elgolensis lived approximately 167 million years ago, during the Middle Jurassic era, a pivotal time when squamates—the group encompassing lizards and snakes—were undergoing significant diversification. This species boasts a captivating mosaic of traits: despite possessing snake-like jaws with hook-shaped teeth akin to those found in modern pythons, it retained a relatively short body and fully developed limbs, characteristics typical of lizards. This unusual combination challenges traditional perspectives on the linear evolution of snakes from lizard ancestors.
The research, recently published in the prestigious journal Nature, represents a decade-long collaborative effort involving scientists from leading institutions, including the American Museum of Natural History, University College London, National Museums Scotland, and the European Synchrotron Radiation Facility in France. By applying state-of-the-art imaging techniques such as high-resolution computed tomography and synchrotron radiation-based scanning, researchers meticulously analyzed the specimen, revealing minute details of its cranial and postcranial anatomy that could not be discerned through conventional fossil preparation methods.
One of the most astonishing revelations from this study is the coexistence of both snake-like and gecko-like anatomical traits within the same individual. Previous fragmentary fossils had suggested the possibility of two distinct animals due to the stark differences in their skeletal features, but Breugnathair demonstrates that such features can indeed be fused in a single species. This finding suggests either that the ancestors of snakes were more morphologically diverse than previously believed, or that snake-like predatory adaptations may have evolved independently among different extinct squamate lineages.
The Parviraptoridae family, to which Breugnathair belongs, was previously known primarily from isolated, incomplete fossils. This discovery therefore fills a critical gap in the fossil record, providing a rare glimpse into the anatomy and ecological role of these early predatory squamates. At nearly 16 inches in length, Breugnathair would have been one of the dominant reptilian predators in its ecosystem, preying on smaller vertebrates including early mammals, younger dinosaurs, and other lizards prevalent in the Jurassic environment of the Isle of Skye.
The Isle of Skye’s Jurassic fossil beds have long been recognized for their importance in illuminating the early evolutionary history of numerous vertebrate groups. This fossil contributes substantially to that narrative by demonstrating that evolutionary pathways may have involved complex mosaics of primitive and derived features. Susan Evans of University College London, co-leader of the study, likened this discovery to finding the top of a jigsaw puzzle box after having assembled the picture from fragmentary pieces, underscoring the importance of this specimen in reconstructing evolutionary lineages.
One of the key questions emergent from the Breugnathair discovery is its precise position within the squamate evolutionary tree. While it exhibits snake-like dental and mandibular morphologies, it is less clear whether it represents a direct ancestor of modern snakes or an unrelated lineage that convergently evolved some snake-like characteristics. The possibility that Breugnathair is a stem-squamate—a basal form predating the divergence of all modern lizards and snakes—raises intriguing questions about early squamate diversification and the selective pressures that shaped their anatomical innovations.
Lead author Roger Benson from the American Museum of Natural History emphasizes that although Breugnathair significantly advances our understanding, the fossil record remains fragmentary, and further discoveries will be crucial to resolving the origins of snake-like traits. The existence of such a morphologically intermediate species highlights the complexity of evolutionary transitions and the need to interpret fossil data within a nuanced framework that accommodates convergent evolution.
Technological advances, such as computed tomography and synchrotron imaging, play a pivotal role in analyzing delicate fossils like Breugnathair. By penetrating the matrix and revealing internal structures without damage, these tools allow scientists to reconstruct skeletal elements and identify features such as tooth implantation, bone articulation, and limb morphology with unprecedented clarity. This integrative methodological approach has become indispensable in paleontology, particularly for understanding the evolutionary trajectories of diverse vertebrate clades.
The anatomical features of Breugnathair elucidate the evolutionary experimentation that characterized the early history of squamates, where combinations of ancestral and derived traits were shuffled in response to ecological challenges. Its unique dental morphology, featuring hook-like teeth adapted for gripping prey, coupled with primitive postcranial traits, suggests a transitional functional morphology that predated the fully limbless, elongate forms characteristic of extant snakes.
This discovery not only enriches our understanding of Jurassic ecosystems but also has broader implications for interpreting evolutionary processes such as convergence, modular evolution, and the tempo of morphological change. It calls for a reevaluation of assumptions regarding the ancestry of snakes, emphasizing that evolutionary innovation may have occurred in modular fashion, with certain traits arising multiple times independently in response to similar ecological pressures.
Future research directions inspired by the discovery of Breugnathair include targeted fossil hunts in Jurassic deposits worldwide to uncover additional specimens that bridge morphological gaps. The integration of advanced imaging with comparative phylogenetic analyses holds promise for constructing a more resolved squamate evolutionary tree, clarifying the origins and diversification of snakes and their kin. Breugnathair stands as a testament to the intricate, mosaic nature of vertebrate evolution, a vivid reminder that the path from lizards to snakes was likely anything but straightforward.
As investigators continue to dissect the nuances of Breugnathair’s anatomy, this fossil fuels anticipation for uncovering the roots of one of the most fascinating reptilian lineages. Its blend of ancient and specialized features attests to the creative potential of natural selection during the Jurassic and invites further exploration into the evolutionary experimentation that defined the age of dinosaurs.
Subject of Research: Mosaic anatomy of early fossil squamates and their evolutionary implications.
Article Title: Mosaic anatomy in an early fossil squamate
News Publication Date: 1-Oct-2025
Web References: https://www.nature.com/articles/s41586-025-09566-y
References: DOI 10.1038/s41586-025-09566-y
Image Credits: Mick Ellison/©AMNH
Keywords: Paleontology, Evolutionary biology, Evolution, Reptiles
